Automatic inference of the language in use via the tags on the question, and

Manual specification of the language in a code block, overriding any language behavior on a question tag

Currently, we have highlighting enabled for a large number of tags, a default set from Stack Overflow or some such. We've already disabled automatic highlighting on a small handful (ios, iphone, php) due to awkward highlighting on questions, but we need to decide what approach to take for a consistent behavior across all tags.

Disable all automatic highlighting, globally, across all tags.

You won't see a lot of highlighting at all, since it needs to be manually specified by the author (it's explained in editing help, but to really do it right takes a dig in m.SO) - but at least there won't be any highlighting of something that isn't code.